NEW CONFIGURE ARCHIVING INTERFACE
In 4.0.0, the new configuration experience is based around the concept of triggers ("if a page is older than 10 days" or "if a page labelled with 'foo'"...) and actions (...then "notify its last modifier"), allowing fine-grained settings and eliminating confusion.
The rules of "who receives what email" are 100% configurable.
To send notifications to users that are not "directly" related to the content (not authors, etc.), configure so-called supervisors.
To route all notifications to a single external mailbox, just set up a Confluence user with that email address and select that as supervisor.
SELECTABLE ARCHIVER USER
Previously, archiving operations (like copying and deleting pages) were executed by a user account automatically selected by the plugin. It lead to some misunderstanding.
The archiver user can now be manually picked. Tip: set up an intuitively named user account (ex: "Wiki Archiver") for that.
...oh, did you see our new docs?